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- The Korean Astronomical Society (The Korean Astronomical Society)
- 계간 (Quarterly)
- ISSN : 1225-4614 (ISSN : 1225-4614)
1225-4614
- DB구축현황 : 1,227건 (DB Construction : 1,227 Articles)
총 게시글 1,227건
페이지 90/123
891
- BESKIN G. M.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.251-252
- 1996
- 원문 바로보기
892
- CANNON RUSSELL
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.367-370
- 1996
- 원문 바로보기
Construction of the 'Two-degree Field' (2dF) instrument on the Anglo-Australian Telescope (AAT) is now virtually complete and commissioning is well underway. The key components are described. Several recent milestones are reported, including the first scientific results. Future prospects and plans are discussed.
893
- LEE YOUNG-WOOK
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.49-51
- 1996
- 원문 바로보기
New population synthesis models, with the effects of metallicity spread and the horizontal-branch (HB) morphology, provide a way to break the well-known age-metallicity degeneracy in the analysis of the integrated light of elliptical galaxies. Our models suggest that the far- UV radiation of these systems is dominated by a minority population of metal-poor, hot HB stars and their post-HB progeny, while the optical radiation is dominated by a metal-rich population. The systematic variation of UV upturn depends on the contribution from metal-poor, hot HB stars and their post-HB progeny, which in turn depends on the ages of old stellar populations in galaxies. Our result implies a prolonged epoch of galaxy formation, in the sense that more massive galaxies (in denser environments) formed first. Our models also suggest that the strenghth of H<TEX>$\beta$</TEX> index is strongly affected by HB stars, and hence previous age estimation without detailed modeling of the HB would underestimate the ages of ellipticals by <TEX>$\~$</TEX>7 Gyr.
894
- WEE SUN-OK
- Journal of the Korean astronomical society = 천문학회지
- 29, n.2
- pp.181-194
- 1996
- 원문 바로보기
We present a study of the metallicity of the old open cluster NGC 1245 , based on the Washington CCD photometry obtained using the 0.6 m telescope at the Sobaeksan Observatory, Korea. NGC 1245 has been known to be a unique cluster among the known open clusters in the sense that the previous metallicity estimates for this cluster are much larger <TEX>$(by\;\sigma)$</TEX> than the value expected from the radial metallicity gradient of the old open clusters in Our galaxy. We have estimated the metallicity of the cluster red giants using the four color-color diagrams, obtaining a value for the mean metallicity of <TEX>$[Fe/H] = -0.04\pm0.05$</TEX> dex. The total error including the error of the metallicity calibration, 0.15 dex, is 0.16 dex. The metallicity estimate of NGC 1245 we have obtained in this study is smaller than previous estimates, and is consistent with the radial metallicity gradient of the old open clusters, showing that the mean metallicity of NGC 1245 is not abnormally high. The reddening, distance, and age of the cluster have also been derived using the isochrones based on the convective overshooting models: the reddening <TEX>$E(B-V) = 0.28\pm0.03$</TEX>; the distance <TEX>$d = 2.5\pm0.2 kpc$</TEX> (the corresponding galactocentric distance is RGC = 10.7 kpc, and the distance from the galactic plane is z = -0.4 kpc); and the age <TEX>$t = 1.1\pm0.1 Gyrs$</TEX>.
895
- KIM SANG CHUL
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.83-84
- 1996
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896
- SHAMSHIEV FAZILIDDIN T.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.73-74
- 1996
- 원문 바로보기
This paper deals with steady-state gravitational potentials of nonaxisymmetric three dimensional systems which rotate with a constant angular velocity. For these systems a class of potentials with local integrals has been found.
897
- KIM YONGGI
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.235-236
- 1996
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Using a phenomenological model for the accretion onto the magnetic white dwarf, we calclliated some optical line profiles from the magnetosphere of such systems. Line profiles of these systems seem to be produced in the magnetosphere of the compact star due to the reemission of X-ray produced near the stellar surface. Some results of our new calculation and the analysis of these results will be presented. Our results show that the model used here can reproduce the observed optical line profiles and open the possiblity to determine the parameters of individual systems.
898
- CHA SEUNG-HOON
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.253-254
- 1996
- 원문 바로보기
To understand the dynamical structures of stellar wind bubble, one and two-dimensional calculations has been performed. Using FCT Code with cooling effects and assuming constant mass loss rate and ambient medium density, we could divide stellar winds into the regime of slow and fast winds. The slow wind driven bubble shows initially radiative and becomes partially radiative bubble in which shocked stellar wind zone is still adiabatic. In contrast., the fast wind driven bubble shows initially fully adiabatic and becomes adiabatic bubbles with radiative outer shell. We also determine analytically the onset of thin-shell formation time in case of fast wind driven bubble with power-law energy injection and ambient density structure. We solve the line transfer problem with numerical results in order to calculate line profile of [OIII] forbidden line.
899
- YUN H. S.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.339-340
- 1996
- 원문 바로보기
In the present study we examine physical characteristics of a thin and rigid magnetic flux tube with a steady flow inside, which is embedded vertically upward in the solar atmosphere. We found from this study that (1) The downward material flow gives rise to a dominant heating in the flux tube which works with the conductive heating in the same direction. However, the upflow flow creates a dominant cooling which works against the conductive heating, resulting in a steeper temperature gradient with a shallower transition region. (2) Since the thickness of the transition region determines the material content in the transition region, a broader transition region of the downflow tube produces a larger differential measure.
900
- LAI S. P.
- Journal of the Korean astronomical society = 천문학회지
- 29, n.suppl1
- pp.327-328
- 1996
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